Method of grinding irregular shafts



April 19, 1932. K. L. HERRMANN METHOD OF GRINDING IRREGULAR SHAFTS FiledNov. '7, 1931 IN V EN TOR. A/2% ATTOR YS.

Patented Apr. 19, 1932 UNITED STATES PATENT OFFICE KARL L. HERRMANN, OFSOUTH BEND, INDIANA, ASSIGNOR TO THE BANTAM BALL BEARING COMPANY, OFSOUTH BEND, INDIANA, A CORPORATION OF INDIANA METHOD or GRINDINGIRREGULAR srmrrs Application filed November 7, 1931.

This invention relates to a method of grinding irregular shafts andparticularly to a method of grinding cylindrical shafts which haveflattened portions or key-ways formed therein, and has for its principalobject the provision of a method for smoothly and accurately grindingcylindrical shafts having flattened portions or key-Ways formed there-19 A further object is the provision of a method for rapidly andeconomically grinding a shaftas described above.

Other objects and advantages will appear as the description proceeds.

The drawings illustrate two examples of such irregular shafts as areparticularly adaptable to the use of the method of this invention, andalso illustrate the method by which irregular shafts may be quickly,smoothly and accurately ground. The drawings, however, are not to beconsidered as limiting the invention, the scope of which is entirelycommensurate with the scope of the co-pending claims.

In the drawings:

Figure 1 illustrates the method of grinding cylinder shafts in acenterless grinder.

Figure 2 is a perspective view of an irregular shaft, a key formed tofit in a slot in the shaft, and a cap formed to fit over one end of theshaft.

Figure 3 is a plan view of the shaft, key and cap illustrated in Figure2.

Figure 4 is a perspective view of a slightly different form of irregularshaft and shows a key formed to fit in the slot in the shaft, and a capadapted to cover the end of the shaft.

Figure 5 is a plan view of the shaft, key

. and cap illustrated in Figure 4. n) Referring to the drawings indetail, Figures 2 and 3 illustrate an irregular shaft generallyindicated at 5, having a cylindrical end portion 10, a reduced portion12 and an intermediate cylindrical portion 14 having formed therein alongitudinal groove or keyway 15. Beyond the intermediate cylindricalportion, the shaft is provided with flat surfaces 16 and 17 and atransverse aperture 18 through the end thereof opposite the cylinbidrical portion 10.

Serial No. 573,623.

From an inspection of this illustration, it will be observed that ashaft of this character would be impossible to grind by ordinary methodsas the key-way breaks into the cylindrical surface and would cause thegrinding wheels to rotate unevenly against the surface of the shaft,thereby producing a shaft having a surface far from accuratelycylindrical. Also the flattened surfaces 16 and 17 make it impossiblefor the shaft to properly rotate on the holding mechanism of acenterless grinder. In order to overcome this difliculty and make itpossible to grind the shaft in an ordinary commercial grinder, a key 20is provided of such dimensions as to fit closely and accurately withinthe slot 15 and form a continuation of the cylindrical surface of theshaft over the slot. This key is made of material of the same hardnessas the shaft and is slightly bent longitudinally so that it may bedriven into the key-way 15 and wedged therein against accidental removalduring the grinding process.

For the flattened end of the shaft, there is provided a cap 22 whichconsists simply of a cylindrical cup which may be machined out of tubingor stamped out of sheet metal. This cup 22 has such an internal diameterand such a thickness that itwill fit securely upon the flattened end ofthe shaft and have an outer surface of substantially the same diameteras the outer surface of the cylinder portions 10 and 14.

l Vhen the key 20 has been inserted in the key-way 15 and the cap 22placed upon the end of the shaft, the shaft may then be insorted in acenterless grinder such as is illustrated in Figure l, and will progressthrough the grinder in the usual manner, all surfaces being smoothly andaccurately ground to the desired dimensions.

Figures 4 and 5 illustrate an irregular shaft somewhat similar to thatillustrated in Figures 2 and 3 but differing in details suflicient- 1yto require a modification of the invention as applied to the shaftillustrated in Figures 2 and 3. v

.The shaft illustrated in Figures 4 and 5 and generally indicated at 30has a cylindrical end portion 35, a notch or groove portion 86, and anintermediate cylindrical portion 38 provided with a groove or key-way40. Beyond the cylindrical portion 38, the shaft is provided with twoflattened surfaces 42 and 433 and an additional flattened surface atright angles to the surfaces 42 and 4-3 and ertending from a point 46adjacent the end of the shaft opposite the cylindrical portion into thecylindrical portion 38 as in-' dicated at i8.

In order to round out the cylindrical portion 38, l have provided a key50 which has a narrow portion 52 adapted to fit into the key-way a0 andwider portion 54; adapted to cover the portion 48 of the flattenedsurface and having a part y cylindrical upper surface adapted to form acontinuation of the surface of the cylindrical portion 38. In thisinstance there is also provided a cup shaped cylindrical cap 60 adaptedto fit upon the flattened end of the shaft 30 and provide a surfacehaving substantially the same dimensions as the surface of the portions35 and 38.

The portion of is formed to fit tightly into the ke -wa O and isslightly bent longitudinally so that it will wedge firmly in thekey-way. When the key 50 and the cap have been inserted on the shaft 30,the shaft may then be inserted in a cent-erless grinder as iilustrated land will a the 1., i. ii

in- Figure l progress through the grinder in the usuai manner.

Referring to Figure 1, it will be observed that the grinder used in thisoperation is of the centerless type and comprises a frame 65, a fixedjournal bearing 66 and a slidable journal bearing 67. Mounted on a shaft68 which rotates in the fixed journal bearing 66 is a grinding wheel 69,and mounted on a shaft "2'0 which rotates in the slidable journalbearing 67 is a similar grinding wheel 72. The slidable journal bearing67 is manually adjusted by means of a crank 78 connected with ascrew 7a.

A. bed plate or block '55 is provided at each side of the grindingwheels 69 and 72. fhe shaft 5 to be ground is placed upon the block 75and forced through between the rapidly rotating grinding wheels 69 and72. During this operation, the distance between the two grinding wheels69 and 72 is adjusted by means of the crank 73 until the shaft is groundto the exact dimensions required.

Owing to the fact that the shaft rotates as it progresses between thegrinding wheels, it will be seen that it is necessary that the shaftshould have a cylindrical surface at both ends thereof so that the axisof the shaft will remain parallel to the axis of rotation of thegrinding wheels, and it is also apparent that the cylindrical surfacebeing ground must be substantially continuous, as any breaks in thecontinuity of the surface will cause the shaft to rotate irregularlybetween the grinding wheels whereby one portion of the shaft may beground away more than another portion, thus producing an uneven surfaceon the shaft.

Having now described my invention and the principal objects andadvantages thereof so that oth rs skilled in the art may clearlyunderstand the same, what I desire to secure by Letters Patent is asfollows:

1. The method of grinding cylindrical surfaces on an irregular shaftwhich comprises, rounding out the irregular portions of the shaft bymeans of keys of approximately the same hardness as the shaft firmlyfixed to the shaft to cover said irregularities and then working theshaft through a centerless grinder.

2. A method of grinding an irregular cylindrical shaft having a key-wayformed in the cylindricalportion thereof, and having a flattened endportion which comprises, inserting a key of approximately the samehardness of the shaft in said key-way, inserting a hollow cylindricalcap upon the flattened end of said shaft and working the shaft through acenterless grinder.

if method of grinding an irregular cylindrical shaft having a key-wayand a fiattened portion in the cylindrical portion thereof, and having aflattened end portion which comprises, forming a key having a narrowportion to fit in said key-way and a wide .portion with a partlycylindrical surface to cov-- er said flattened portion and forming acontinuation of the surface of said cylindrical portion, inserting ahollow cylindrical cap upon. the flattened end of said shaft and working the shaft through a centerless grinder.

Signed by me at South Bend, Indiana, this i day of November, 1981.

KARL L, HERRMANN.

